This invention relates to the production of stearidonic acid from a mixture of fatty acids in which it is present as a minor constituent.
It is known that essential fatty acids of the n-3 series (nomenclature defined by the position of the first double bond from the methyl group) lead by a chain reaction to series 3 prostaglandins which inhibit the aggregation of blood platelets.
The first element of this chain is .alpha.-linolenic acid (ALA, C 18:3 .DELTA.9,12,15) of which the conversion into stearidonic acid (SA, C 18:4 .DELTA.6,9,12,15) is attributable to the activity of the enzyme .DELTA.6 desaturase which is shown to weaken with age and as a result of certain diseases. The synthesis of the series 3 prostaglandins is thus compromised. To overcome this weakness of the organism, it is proposed to introduce stearidonic acid directly into the body.
Japanese patent application 86 050 752 relates to a process for the separation of stearidonic acid from fish oil which comprises the steps of converting the fatty acids present therein into their ethyl esters, treating the ethyl esters by molecular distillation and collecting the head fraction, reacting it with urea in methanol, collecting the unreacted fraction and, finally, separating a fraction enriched with ethyl ester from the stearidonic acid by two successive operations of reverse-phase partition chromatography.
A purity of 85% by weight is thus obtained for a yield of 1.8%, based on the oil used, which represents a recovery of 48% of the stearidonic acid present in the starting material.
In addition, European patent 178 442 relates to the enrichment of blackcurrant seed oil with .gamma.-linolenic acid (GLA, C 18:3 .DELTA.6,9,12) by the double complexing with urea of a mixture of fatty acids eminating from the saponification of blackcurrant oil, followed by high-performance reversephase liquid chromatography. According to this patent, separation appeared particularly difficult, enrichment of the mixture only appearing possible in regard to its major constituent, .gamma.-linolenic acid.